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Full Record for Micrograph 695

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Micrograph no
695
Brief description
Cu-4.5 wt% P
Keywords
alloy Link to MATTER Glossary entry for alloy, bronze Link to MATTER Glossary entry for bronze, copper, coring Link to MATTER Glossary entry for coring, dendrite Link to MATTER Glossary entry for dendrite, hypoeutectic Link to MATTER Glossary entry for hypoeutectic, metal, phosphorus Link to MATTER Glossary entry for phosphorus
Categories
Metal or alloy
System
Cu-P   Link to phase diagram
Composition
Cu 95.5, P 4.5 (wt%)
Standard codes
Reaction
Processing
Applications
This alloy has no practical applications
Sample preparation
Etch in ferric chloride
Technique
Reflected light microscopy
Length bar
400 μm
Further information
This is an example of a hypoeutectic alloy. On slow cooling the liquid first solidified at approximately 940ºC as copper rich dendrites. The composition of the remaining liquid became increasingly rich in phosphorus until it solidified as a eutectic (8.38 wt% P) at the eutectic temperature of 714ºC. Note that the dendrites are cored - the different contrast after etching indicated that the composition varies with position in the dendrites. This is caused by non-equilibrium solidification. The cooling rate was too rapid for equilibrium to be maintained between the solid and the liquid phases.

This alloy has no practical applications. Phosphor bronzes usually contain 5 wt% Sn for solid solution strengthening with 0.2 wt% P for interstitial solution strengthening. They have high strength and corrosion resistance and are usually used for springs.
Contributor
Dr J Marrow
Organisation
Department of Materials Science, University of Manchester and UMIST
Date
07/11/02
Licence for re-use
Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales
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